Worksites, such as, for example, mine sites, landfills, quarries, construction sites, etc., commonly undergo geographic alteration by machines and/or workers performing various tasks thereon. For example, at a coal mining site, mounds of coal are continually moved by dozers about the site, onto conveyors, into chutes, etc., to prepare the coal for transport. Likewise, on an excavation site, terrain is altered by digging, grading, leveling, or otherwise preparing the terrain for various uses.
It has become useful to map terrain in some applications. For instance, it is advantageous to map worksite terrain for remotely aiding or controlling excavation, determining progress towards completion of tasks, calculating material ingress and egress, and/or identifying worksite inefficiencies or other trends.
One example of a terrain mapping system is described in U.S. Pat. No. 6,608,913 (the '913 patent) issued to Hinton et al. on Aug. 19, 2003. The '913 patent describes a self-contained mapping and positioning system for use in underground mining applications. Specifically, a survey system including a laser scanner attached to an underground, remotely-operated mining vehicle is disclosed. As the vehicle advances through the mine, the scanner scans the mine. The scanned data is converted into point cloud data representing the surface of the mine. The survey system then stores the point cloud data in a three-dimensional database, which is used to navigate the vehicle through the mine.
Although the survey system of the '913 patent may adequately map the surface of the mine, it may be inefficient. For example, if the mine is surveyed at the same location multiple times, the three-dimensional database may be updated with redundant point cloud data, even if no changes to the mine surface have occurred since the prior scan. In addition, the survey system of the '913 patent may be unable to distinguish the mine surface from other structures in the mine (e.g., another mining vehicle). If scanned, these structures might be incorporated into the three-dimensional database, creating an inaccurate map of the mine terrain.
This disclosure is directed to overcoming one or more of the problems set forth above.